Category: 4. Human Hearing, Speech and Psychoacoustics

Since speech and hearing must be compatible, it is not surprising to find that the speech frequency range corresponds to the most sensitive region of the ear’s response (Section 4.3.2) and generally extends from 100 to 10 000 Hz. The general mechanism for speech generation involves the contraction of the chest muscles to force air out of…

Another form of sensory‐neural hearing loss is presbycusis. This loss in hearing sensitivity occurs in all societies. Figure 4.24 shows the shift in hearing threshold at different frequencies against age [52]. As can be seen, presbycusis mainly affects the high frequencies, above 2000 or 3000 Hz. It affects men more than women. The curves shown in Figure 4.24 show the…

There are several causes of sensory‐neural hearing loss and all are associated with disorders of the inner ear, the auditory nerve fibers, the auditory cortex in the brain, or combinations of all three. Unlike conductive deafness, sensory‐neural deafness is often most severe at higher frequencies. Background noise can thus mask the consonants in speech and…

This normally manifests itself as a fairly uniform decrease in hearing over most frequencies. Background noise usually causes people to speak louder and those with conduction deafness can then often hear. This type of deafness can normally be overcome by a hearing aid with sufficient amplification. There are several causes of conduction deafness, some of…

Some are born with the severe handicap of deafness. Others suffer sudden hearing loss later in life or (much more commonly) gradually lose their hearing over a period of time. For all these persons, deafness is a crippling loss of one of the most important senses. Deafness can be very slight or complete. There are…

Figure 4.23 shows a block diagram of an empirical Zwicker‐type dynamic loudness meter (DLM) that includes the spectral and temporal loudness processing portrayed in Figures 4.21 and 4.22 [22]. First, the spectral processing (1 and 2) shown in Figure 4.22 using the critical band filter bank concept, upward spread of masking (7), and spectral summation (8) are illustrated. Second, the temporal processing discussed in relation to Figure 4.23 is observed as shown in the…

The term loudness adaptation refers to the apparent decrease in loudness that occurs when a subject is presented with a sound signal for a long period of time [45]. The effect has been studied extensively by presenting tones for an extended period of time to one ear and then allowing the subject to adjust the level of…

The loudness of sounds was discussed in Sections 4.3.2 and 4.3.5, where it was shown that A‐weighted sound pressure level measurements underestimate the loudness of broadband noise. (See Figure 4.16.) Methods to evaluate the loudness of broadband noise based on multiband frequency analysis have been devised by Stevens [44], Kryter [16], and Zwicker [12]. The Stevens method was originally…

It is well known from music that humans do not hear the frequency of sound on a linear scale. A piano keyboard is a good example. For each doubling of frequency (known as an octave), the same distance is moved along the keyboard in a logarithmic fashion. If the critical bands are placed next to…

Another important factor is the way that the ear analyzes the frequency of sounds. The critical band concept already discussed in Section 4.3.5 is important here as well. It appears that the human hearing mechanism analyzes sound like a group of parallel frequency filters. Figure 4.18 shows the bandwidth of these filters as a function of their center frequency.…